Integrated ground-based remote sensing sensors for glaciological monitoring

Glaciological processes, such as glacier break-offs, snow/ice avalanches, can threaten the population, urban areas and infrastructures. For their potential hazard, it is necessary to study their activity in order to understand their possible geophysical dynamics evolution and to develop strategies of preventive alert and mitigation actions. Therefore, the first step of this observation-alert-mitigation framework is the monitoring of such phenomena. One of the most relevant parameters to be investigated is the surface deformation, as it provides a direct measurement of the process activity. The gravitational slope processes are common in mountain environment and hence they are often placed in harsh and remote areas. Therefore, a practical approach for their monitoring is the adoption of remote-sensing apparatuses, which allow at not accessing into possible perilous investigated areas, with consequent reduction of human resources and risks. The remote sensing systems can be classified into two main categories: i) systems installed on aerospace platforms and ii) ground-based sensors. The first group provides data at global scale and the recent free availability of satellite constellations such as Sentinel 1 e Sentinel 2 is making their use widely studied. However, such systems suffer limitation of low temporal resolution, with revisiting time of days or weeks. The data availability of specific and localised areas is not always guaranteed and/or it can require high financial costs (e.g., airborne surveys, private satellite constellations). Moreover, complex geometries, typical of gravitational processes located in mountain areas, can affect the data acquisition. By contrast, ground-based apparatuses are able to acquire data in environments with complex geometry. Furthermore, they can often operate in continuous, therefore providing data with high spatio-temporal resolution. In general, a single monitoring system is able to measure specific parameters that can partially describe the state and the evolution of the investigated phenomenon. Therefore, a common approach consists in adopt different sensors and to collect separately their measurements to obtain a more comprehensive outline of the process. However, the independent analysis of the data of each sensor might not be sufficient to exploit all the available information. Rather, merging the different data in a coupled model can provide more informative results. Moreover, the data coupling allows at exploiting the qualities and potentialities of each sensor and to minimise their limits. However, the realisation of an integrated system requires an accurate assessment of the instrument capacities. Therefore, the first step of such realisation involves the characterisation of the monitoring devices. Moreover, the development of specific and innovative processing techniques might be necessary to optimise the coupling process. The methodologies developed for processing data of single and coupled sensors can be applied to practical case studies where the monitoring of gravitational slope phenomena can yield results about their present geophysical state, their dynamics and their possible evolution. This text presents a collection of articles published in international scientific journals. The papers represent the work conducted during the PhD whose focus was the development of methodologies for coupling data collected by different sensors to monitor glaciological processes